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Abstract:

A packet transmission system having existing null packets is provided. The
system comprises a transmitter side transmitting information packets
having null packets filled with redundancy information or parity check
information; and a receiver side receiving the information packets and
decoding the information packets using a predetermined decoding method;
whereby the information packets are transmitted only once.

Claims:

1. A packet transmission system having existing null packets, the system
comprising:a transmitter side transmitting information packets having
null packets filled with redundancy information or parity check
information; anda receiver side receiving the information packets and
decoding the information packets using a predetermined decoding method;
whereby the information packets are transmitted only once.

2. The system of claim 1, wherein the predetermined decoding method uses a
LDPC code.

3. The system of claim 2, wherein the H matrix of the LDPC code is H=PI.

4. The system of claim 3, wherein the P matrix, sub-matrix has a set of
predetermined number of `1`s on a row with positions in the row randomly
distributed.

5. The system of claim 2, wherein an associated generation matrix G is
defined as G=P.

6. The system of claim 1, wherein the predetermined decoding method uses a
Turbocode.

7. The system of claim 1, wherein the predetermined decoding method uses a
convolution code.

8. A receiver in a packet transmission system having existing null
packets, the receiver comprising:a decoder for decoding received
information packets having null packets filled with redundancy
information or parity check information using a predetermined decoding
method; whereby the information packets are transmitted only once.

15. In a packet transmission system having existing null packets
transmitted therein, a method comprising the steps of:filling the at
least one null packet with redundancy information or parity check
information; andtransmitting information packets including the filled
null packets.

16. The method of claim 15 further comprising the step of receiving the
information packets and decoding the information packets using a
predetermined decoding method; whereby the information packets are
transmitted only once.

17. The method of claim 16, wherein the predetermined decoding method
comprises using a LDPC code.

18. The method of claim 17, wherein the H matrix of the LDPC code is H=PI.

19. The method of claim 18, wherein the P matrix, sub-matrix has a set of
predetermined number of `1`s on a row with positions in the row randomly
distributed.

20. The method of claim 17, wherein an associated generation matrix G is
defined as G=P.

21. The method of claim 15, wherein the null packets are randomly
positioned within a transmitted frame.

Description:

FIELD OF THE INVENTION

[0001]The present invention relates generally to packet transmission, more
specifically the present invention relates to method and apparatus for
non-repetitive transmission of packets.

BACKGROUND

[0002]Communications systems are known to retransmit a packet under
certain pre-determined conditions. However, transmitting the packet two
or more times may be undesirous in certain systems such as territorial
television systems.

[0003]Further, known communications systems transmit packets having null
packets interposed between information packets. Therefore, it is desirous
to use the null packets for such purposes as parity check or fill same
with redundancy information associated with the information packets.
Thereby with proper decoding the information packets need only be
transmitted once.

SUMMARY OF THE INVENTION

[0004]A packet transmission system that transmits only once a set of
packets comprising information packets and redundancy or parity check
packets is provided.

[0005]A receiver receiving only once a set of packets comprising
information packets and redundancy or parity check packets is provided.

[0006]A decoder decoding a set of received packets comprising information
packets and redundancy or parity check packets is provided.

[0007]A packet transmission system having existing null packets is
provided. The system comprises a transmitter side transmitting
information packets having null packets filled with redundancy
information or parity check information; and a receiver side receiving
the information packets and decoding the information packets using a
predetermined decoding method; whereby the information packets are
transmitted only once.

[0008]A receiver in a packet transmission system having existing null
packets is provided. The receiver comprises a decoder for decoding
received information packets having null packets filled with redundancy
information or parity check information using a predetermined decoding
method; whereby the information packets are transmitted only once.

[0009]In a packet transmission system having existing null packets
transmitted therein, a method is provided. The method comprises the steps
of: filling the at least one null packet with redundancy information or
parity check information; and transmitting information packets including
the filled null packets.

BRIEF DESCRIPTION OF THE FIGURES

[0010]The accompanying figures, where like reference numerals refer to
identical or functionally similar elements throughout the separate views
and which together with the detailed description below are incorporated
in and form part of the specification, serve to further illustrate
various embodiments and to explain various principles and advantages all
in accordance with the present invention.

[0011]FIG. 1 is an example a frame having null packets in accordance with
some embodiments of the invention.

[0012]FIG. 2 is an example of a method in accordance with some embodiments
of the invention.

[0013]FIG. 3 is an example of a H matrix in accordance with some
embodiments of the invention.

[0014]Skilled artisans will appreciate that elements in the figures are
illustrated for simplicity and clarity and have not necessarily been
drawn to scale. For example, the dimensions of some of the elements in
the figures may be exaggerated relative to other elements to help to
improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION

[0015]Before describing in detail embodiments that are in accordance with
the present invention, it should be observed that the embodiments reside
primarily in combinations of method steps and apparatus components
related to transmits only once a set of packets comprising information
packets and redundancy or parity check packets. Accordingly, the
apparatus components and method steps have been represented where
appropriate by conventional symbols in the drawings, showing only those
specific details that are pertinent to understanding the embodiments of
the present invention so as not to obscure the disclosure with details
that will be readily apparent to those of ordinary skill in the art
having the benefit of the description herein.

[0016]In this document, relational terms such as first and second, top and
bottom, and the like may be used solely to distinguish one entity or
action from another entity or action without necessarily requiring or
implying any actual such relationship or order between such entities or
actions. The terms "comprises," "comprising," or any other variation
thereof, are intended to cover a non-exclusive inclusion, such that a
process, method, article, or apparatus that comprises a list of elements
does not include only those elements but may include other elements not
expressly listed or inherent to such process, method, article, or
apparatus. An element proceeded by "comprises . . . a" does not, without
more constraints, preclude the existence of additional identical elements
in the process, method, article, or apparatus that comprises the element.

[0017]It will be appreciated that embodiments of the invention described
herein may be comprised of one or more conventional processors and unique
stored program instructions that control the one or more processors to
implement, in conjunction with certain non-processor circuits, some,
most, or all of the functions of transmits only once a set of packets
comprising information packets and redundancy or parity check packets
described herein. The non-processor circuits may include, but are not
limited to, a radio receiver, a radio transmitter, signal drivers, clock
circuits, power source circuits, and user input devices. As such, these
functions may be interpreted as steps of a method to perform transmiting
only once a set of packets comprising information packets and redundancy
or parity check packets. Alternatively, some or all functions could be
implemented by a state machine that has no stored program instructions,
or in one or more application specific integrated circuits (ASICs), in
which each function or some combinations of certain of the functions are
implemented as custom logic. Of course, a combination of the two
approaches could be used. Thus, methods and means for these functions
have been described herein. Further, it is expected that one of ordinary
skill, notwithstanding possibly significant effort and many design
choices motivated by, for example, available time, current technology,
and economic considerations, when guided by the concepts and principles
disclosed herein will be readily capable of generating such software
instructions and programs and ICs with minimal experimentation.

[0018]Referring to FIGS. 1-3, in FIG. 1 a frame subject to transmission is
provided. The frame comprises at least one null packet with no
information contained therein. The null packets are the space wherein a
transmitter transmits no information. Typically null packets are packets
contain zeros. The present invention proposes filling the null packets
with encoding information such that a suitable decoder can decode the
frame without re-transmitting any packet in the frame. The null packet
can be filled with such information as redundancy information. Further,
code length may be infinitely long. In practice, the length is any
predetermined, finite length. In the frame for transmission, interposed
between data packets are null packets 10. This is typical of a
communication system such as an OFDM system.

[0019]In FIG. 2, a flowchart is provided. Provide a Frame with null
packets (Step 202). Fill the null packets with more encoding information
including redundancy information or parity check information (Step 204).
Transmit the frame (Step 206). Receive and decode using a predetermined
decoding method such as LDPC, Turbocode, convolution code method (Step
208). A special type of LDPC code is contemplated herein in a binary
erasure channel in which probability parameters such as least likelihood
ratio (LLR) is not required.

[0020]The special type of LDPC code is generated as follows. As shown in
FIG. 3, the H matrix is defined as H=PI. Where each row of P has a set of
predetermined number of `1`s with there positions in row randomly
distributed. Data information bits are not transmitted. Instead, in
combination with the erasure position of the P matrix with I matrix, LDPC
decoding is achieved. At the encoding end, generation matrix G is defined
as G=P. Therefore, v=uPT. By way of example, a LS digital fountain
code are as follows. Information bits k=5, encoding bits n=10. Degree
distribution satisfies the following v(x) 0.5x+0.5x2. There are 5
check nodes with degree 1, and 5 check nodes with degree 2. P, the first
5 columns of H matrix corresponds to information bits. The last 10
columns, I, corresponds to check bits. Let left hand side (part of P)
first 5 rows have degree 1 with there exact position in a row randomly
chosen. Let left hand side (part of P) last 5 rows have degree 2 with
there exact position in a row randomly chosen. In other words, for the
first 5 rows of P posses degree 1 and 6-10th rows posses degree 2.

[0021]The present invention may be used in both wireline and wireless
communications systems. Broadcasts such as the WiMax system is
contemplated in the present invention.

[0022]The present invention contemplates using convolutional codes, turbo
codes, or low density parity check codes (LDPC). Using LDPC codes have
advantages in that using a simple probabilistic decoding technique, a
very superior in performance can be achieved. The LDPC code is defined by
a parity check matrix, wherein most elements are `0`. In other words,
LDPC code is defined by a parity check matrix H in which the number of
`1`s in each row and column is very small in comparison with the number
of `0`s. The LDPC code is used to determine if a received signal has been
subject to normal decoding. In other words, if the product of a coded,
received signal and the parity check matrix becomes `0` or check-sum
equal zero, no reception error occurs. As can be seen, for the LDPC code,
a predetermined parity check matrix H is first designed such that a
product of the parity check matrix and all coded received signals becomes
`0`, and then a coding matrix for coding a transmission signal is
inversely calculated according to the predetermined parity check matrix
H. Typically, a probabilistic iterative decoding technique is used. By
using simple parity check equations, a probabilistic iterative decoding
technique finds a codeword that is the best probabilistical approximation
of the codeword in that a product of a received signal vector and the
parity check matrix is `0`. Two decoding methods are typically used. They
are sum-product method and a method for calculating a transmitted message
using a log likelihood ratio (LLR). A sum-product method finds a codeword
by performing soft-decision iterative decoding using a probability value.
In other words, the sum-product method determines a codeword designed
such that a product of a received signal vector and the parity check
matrix is `0` by means of updating a probability value of each bit using
characteristics of a received vector and a channel during every iterative
decoding. In the method for calculating a transmitted message using a log
likelihood ratio (LLR), it is similar to the sum-product method, except
that an LLR value is used instead of the actual probability value for
calculating the transmitted message.

[0023]The present invention contemplates using punctured LDPC codes. Using
an erasure channel, the generator matrix of the punctured LDPC code is
identical as the H matrix.

[0025]A packet transmission system having existing null packets is
provided. The system comprises a transmitter side transmitting
information packets having null packets filled with redundancy
information or parity check information; and a receiver side receiving
the information packets and decoding the information packets using a
predetermined decoding method; whereby the information packets are
transmitted only once.

[0026]A receiver in a packet transmission system having existing null
packets is provided. The receiver comprises a decoder for decoding
received information packets having null packets filled with redundancy
information or parity check information using a predetermined decoding
method; whereby the information packets are transmitted only once.

[0027]In the foregoing specification, specific embodiments of the present
invention have been described. However, one of ordinary skill in the art
appreciates that various modifications and changes can be made without
departing from the scope of the present invention as set forth in the
claims below. Accordingly, the specification and figures are to be
regarded in an illustrative rather than a restrictive sense, and all such
modifications are intended to be included within the scope of present
invention. The benefits, advantages, solutions to problems, and any
element(s) that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical, required,
or essential features or elements of any or all the claims. The invention
is defined solely by the appended claims including any amendments made
during the pendency of this application and all equivalents of those
claims as issued.

[0028]Terms and phrases used in this document, and variations thereof,
unless otherwise expressly stated, should be construed as open ended as
opposed to limiting. As examples of the foregoing: the term "including"
should be read as mean "including, without limitation" or the like; the
term "example" is used to provide exemplary instances of the item in
discussion, not an exhaustive or limiting list thereof; and adjectives
such as "conventional," "traditional," "normal," "standard," and terms of
similar meaning should not be construed as limiting the item described to
a given time period or to an item available as of a given time, but
instead should be read to encompass conventional, traditional, normal, or
standard technologies that may be available now or at any time in the
future. Likewise, a group of items linked with the conjunction "and"
should not be read as requiring that each and every one of those items be
present in the grouping, but rather should be read as "and/or" unless
expressly stated otherwise. Similarly, a group of items linked with the
conjunction "or" should not be read as requiring mutual exclusivity among
that group, but rather should also be read as "and/or" unless expressly
stated otherwise.

Patent applications by Lei Chen, Santa Clara, CA US

Patent applications by LEGEND SILICON CORP.

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